Great answer. I agree. As soon as the user enters the field, pop up the calendar. It also seems to help the user to really relate to the date they're picking. If the current month appears, they have to consider the numeric day, also the day of the week. It's a nice subliminal double check. I added a "clear date" button on the calendar I use, just in case you needed to remove a date (i.e. to "unschedule" something).